I really don't know much about laptops, but I know exactly how you feel. My birthday is on the 29th and it is a pain no matter how much your mum and dad try to help.
I'm sorry I can't suggest a laptop at your price, but I wish you well, and hope you get what you want for both your birthday and Xmas.
Tell your mum you are going to have an official birthday in June just like the queen.
PS. My mums birthday was on the 28th, look at what a wonderful present she got!!!